Japan joined an alliance with Germany and Italy. They were known as an Axis. Apponants of the Axis were Britian, France and the Soviet Union. America cut off oil and other supplies from Japan that were vital.
Rebels from Japan forced the Shogun to step down from the thrown. Samurai made Japan modernize so that Japan could keep up with other countries. Meiji reformers got hundreds of Japanese to go to europe to study western government, industry, and military organization.
In 1853, four American ships anchored Tokyo Bay. Japan did not want to trade with America, but America wanted to keep japans ports open for trade. Japan refused to keep their ports open, so America FORCED them to trade. Japan was upset because they wanted to be their own seperate isolated nation.